Radiotherapy is used to treat cancers and other ailments in mammalian (e.g., human and animal) tissue. An exemplary radiotherapy is provided using a linear accelerator (LINAC), whereby a target (e.g., a tumor) is irradiated by high-energy particles (e.g., electrons, photons, ions and the like). In a typical LINAC-based radiation treatment, multiple radiation beams are directed towards the target from different angles.
The surrounding normal tissue is often called an organ at risk (OAR). To prevent OARs from the severe collateral damage caused by the radiation beams, the doses received by these OARs should be limited to a certain level. Such limitations on the doses received by the OARs, often called constraints, need to be satisfied during treatment planning.
Treatment planning is a process involving determination of specific radiotherapy parameters (e.g., radiation beam angles, radiation intensity level at each angle, etc.) for implementing a treatment goal under the constraints. The outcome of the treatment planning exercise is a radiotherapy treatment plan, hereinafter also referred to as a treatment plan or simply a plan. A typical treatment planning process includes delineating one or more targets and one or more OARs from a medical image of the patient, specifying radiation beam angles, or a range of angles in the case of an arc plan, and determining an aperture shape or shapes and radiation intensity levels for each shape at each beam angle. The combination of shape, intensity, collimator angle, and jaw settings at each gantry angle is called a control point and it this information that is transferred to the delivery device to dictate the machine delivery. Optimization is usually carried out with respect to one or more plan parameters to reduce beam-on time, improve dose uniformity, etc.
Creation of a treatment plan can be a time-consuming process where a planner tries to comply with various treatment objectives or constraints, considering their individual importance to produce a treatment plan which is clinically acceptable. Therefore, it is desirable to reduce the planning time with an improved radiotherapy treatment planning workflow.